import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Queue;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: syyyy
 * Date: 2025-08-12
 * Time: 15:15
 */
public class MyStackUseQueue {
    public Queue<Integer> qu1;
    public Queue<Integer> qu2;

    public MyStackUseQueue(){
        qu1=new LinkedList<>();
        qu2=new LinkedList<>();
    }

    public void push(int x){
        if(empty()){
            qu1.offer(x);
        } else if (qu1.isEmpty()) {
            qu1.offer(x);
        }else{
            qu2.offer(x);
        }
    }

    public int pop(){
        if(empty()){
            return -1;
        }
        if(!qu1.isEmpty()){
            int size=qu1.size();
            for (int i = 0; i < size-1; i++) {
                qu2.offer(qu1.poll());
            }
            return qu1.poll();
        }else{
            int size=qu2.size();
            for (int i = 0; i < size-1; i++) {
                qu1.offer(qu2.poll());
            }
            return qu2.poll();
        }
    }

    public int top() {
        if(empty()){
            return -1;
        }
        if(!qu1.isEmpty()){
            int size=qu1.size();
            int val=0;
            for (int i = 0; i < size; i++) {
                val=qu1.poll();
                qu2.offer(val);
            }
            return val;
        }else{
            int size=qu2.size();
            int val=0;
            for (int i = 0; i < size; i++) {
                val=qu2.poll();
                qu1.offer(val);
            }
            return val;
        }
    }

    public boolean empty() {
        return qu1.isEmpty()&&qu2.isEmpty();
    }
}
